The invention relates to a multiple beam charged particle optical system comprising:
a charged particle source for generating a plurality of charged particle beamlets,
charged particle optics for directing the charged particle beamlets from the charged particle source towards a target, said charged particle optics comprising one or more electrostatic lens arrays, each comprising two or more array electrodes for generating a plurality of electrostatic lenslets, wherein each lenslet is arranged for focusing a corresponding charged particle beamlet.
Such a system is for example employed in a maskless charged particle beam lithography assembly for projecting one or more charged particle beamlets onto a target for writing an image or pattern onto said target.